Data signal reproduced from disks suffer greater waveform distortions and poorer error rates as the recording density is higher, failing to obtain normal reproduced data. Since data are recorded on and reproduced from disks in each sector (unit recording area), their waveform distortions vary from sector to sector. It has been customary to equalize reproduced data signals with an equalizer having fixed tap coefficients. Therefore, the waveform distortions are smaller in some sectors and greater in other sectors. It is thus necessary to determine optimum tap coefficients for each sector for equalizing reproduced data signals.
One proposal is to store all data of a sector in a memory and then determine optimum tap coefficients for waveform equalization. However, this proposal results in an increase in the delay time and an increase in a circuit scale such as of the memory. According to another proposal, determine optimum tap coefficients for waveform equalization are determined by data in a sector, and are used as determine optimum tap coefficients for waveform equalization for a reproduced data signal in another sector. If, however, the amount of data used to determine the optimum tap coefficients for waveform equalization, then a poorer error rate will result when reproduced data signals are equalized for waveform using the optimum tap coefficients thus determined. Furthermore, if the data used to determine the optimum tap coefficients for waveform equalization contain an error, then when reproduced data are equalized for waveform using the optimum tap coefficients thus determined, the error rate of the reproduced data is increased.
In view of the above problems, the present invention proposes an apparatus for recording data, an apparatus for reproducing data, an a method of reproducing data to effect stable, reliable, and quick waveform equalization of reproduced data signals with a small-scale circuit upon reproduction of data.